1. Field of the Invention
The present invention relates to a process for manufacturing a developing blade for use in the developing device of a copier such as a laser printer and a metal mold for a developing blade.
2. Description of the Prior Art
Heretofore, in an electrophotographic copier or a copier such as a laser printer, an electrostatic latent image is formed on a photosensitive drum, toner is adhered to this electrostatic latent image by a developing device to visualize it, and this image is transferred to a recording medium such as paper to form an image.
FIG. 7 shows the outline of a developing device of the prior art. In this developing device 50, toner 52 is contained in a housing 51 as a developer and supplied to the surface of a developing roll 55 by means of a toner feed roll 54 while it is stirred by a stirrer 53. The toner 52 supplied to the surface of the above developing roll 55 is controlled to become a uniform thin layer by a developing blade 30 while the developing roll 55 is turned and friction charged to be limited to a predetermined film thickness, and this friction charged toner 52 is carried to a developing area opposite to the above developing roll 55 of the photosensitive drum 56 to be adhered to an electrostatic latent image formed on the surface of the above photosensitive drum 56.
FIG. 8 shows an example of the developing blade of the above prior art. This developing blade 30 is a prolonged member comprising a metal plate 31 which is a plate spring as a support member having one end fixed to the above housing 51 and a blade body 32 which is made of an elastic material such as urethane or rubber, has a projecting sectional form and sandwiches the other end of the metal plate 31. The developing blade 30 is generally manufactured by insert molding using the above metal plate 31 as an insert member.
FIGS. 9(a) and 9(b) show an example of the process for manufacturing a developing blade of the prior art. This developing blade 30 is manufactured by installing the prolonged metal plate 31 shown in FIG. 9(b) as an insert member in the cavity 43 of a metal mold 40 for forming the blade body 32, which consists of a fixed mold 41 and a movable mold 42, in such a manner that its short side projects into the above cavity 43, introducing a rubber material or resin material injected from an unshown injection device into the above cavity 43 from a large number of gates 44 formed above a portion corresponding to the blade body 32 of the above cavity 43 to transfer mold it and solidifying it (refer to patent document 1, for example).
As for the process for manufacturing a developing blade, as shown in FIG. 10, there is proposed a process in which a tab portion 33 extending in the longitudinal direction of the above blade body 32 is formed at the end in the longitudinal direction of the blade body 32 and the gate 45 of an unshown hot runner is formed in this tab portion 33 as a gate for injecting a resin. Thereby, the blade body 32 having a smooth surface can be manufactured by removing the surface distortion of the blade body 32 (refer to patent document 2, for example).
[patent document 1] JP-A 11-231647 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”)
[patent document 2] JP-A 2001-42639